Apparatus for orienting cores



Oct. 15. 1940. PEARSON 2,217,768

APPARATUS FOR ORIENTING CORES Filed Nov. 5, 1937 5 Sheets-Sheet lM/VEIVTO F W/T VESS:

5 Sheets-Sheet 2 n 256 ii 5M);-

INH. :1... :Tit-.-..l----..-----l|- J; M. FEARS 0N AYPARATUS FORORIENT'ING CORES Filed NOV. 5, 193

Oct. 15. 1940.

Barsafi W/T/VESS:

Oct. 15, 1940. J. M. PEARSON 2,217,768

APPARATUS FOR ORIENTING CORES Filed Nov. 5, 1937 5 Sheets-Sme t sAWE/V70)? 3v v /yw I AIraP/m J J.

Oct. ,15, 1940- Y J. M. PEARSON 2,217,768

APPARATUS FOR ORIENTING CORES Filed Nov. 5, 1937 5 Sheets-Sheet 5Patented Oct. 15, 1940 STATS PAT N'r OFfiE 2,217,768 I APPARATUS Fononmnrmo cones Application November 5, 1937, Serial No. 172,988

'1 Claims.

This invention relates to a method and apparatus for orienting cores bythe determination of the magnetic characteristics thereon As described,for example, in Herrick Patent 1,792,639, dated February 17, 1931, it ispossible to determine to a fair degree of accuracy the dip .and strikeof strata penetrated by a bore hole if measurements are made toascertain the magnetic polarization of a core taken at the location ofthe strata. o

The assumption borne out by observations is that in a magneticallypolarized core the axis of polarization generally originally coincidedin direction and sense with the earths field and that in a. ,coreshowing an axis of maximum susceptibility, that axis originallycoincided in direction with the. axis of the earths field, though in thelatter case the susceptibility axis is without sign.

In making such determinations, the magnetic polarity or axis of maximumsusceptibility of the core may be determined by means of an apparatus ofthe type generally disclosed in said Herrick patent, which, brieflystated, constitutes a magnetometer capable of determining the magneticnorth or susceptibility axis of the core. The magnetic polarity orsusceptibility axis is marked on the core following the use of suchapparatus, and by suitable measurements there can be then determined theapparent dip and strike of a bedding plane appearing in the core withrespect to the magnetic north or susceptibility axis so indicated.Further calculations to determine the relation of dips and strikes tothe earth may then be made, either. numerically or by use of anapparatus such.as that disclosed in'my application Serial No. 146,739,filed June '7, 1937. The present invention has two broad objects,

first theimprovement of apparatus for better de- 49 termining themagnetic properties of cores and second an improved'method of makingdeterminations with such apparatus (includingpreparation of cores)whereby more thorough analysis of the magnetic properties of cores maybe made 45 than by methodsh'eretofore used.

The improved apparatus may be briefly outlined as comprising an astaticmagnet system, adjacent which the core may be mounted for slow rotation,together with a photographic recording 50 means whereby movements of theastatic magnet v system may 'e accurately recorded over a substantialperiod of time, the core rotating on its axis quite slowly in view ofthe delicacy and consequent long period of the magnet system. The

-55 objects of the invention relating to the appara.

(or 17mm) tus are particularly concerned with various arrangements anddetails whereby the determinations may be carried out with a high degreeof accuracy and particularly without influence due to extraneousmagnetic fields. The invention 5 also contemplates the provision in theapparatus of means for accurately supporting the core so as to providefor repeated observations .consistent with each other. Theaccomplishment of these and other objects relating to the apparaw tuswill become clear from the description which follows. 1

The primary object of the invention with respect to the method is tocarry out measurements of the magnetic properties of cores in such fash-15 ion that the various magnetic properties may be individuallydetermined and segregated from each other. In most cores it may besuspected that the magnetic properties might result first from definitepolarization, secondly from a more 29 or less uniform condition ofanisotropic susceptibility which may exhibit itself as a general axisfor the whole core and anisotropic susceptibility or polarizationconditions, or both, resulting from local inclusions in the core ofmaterials having 25 magnetic properties differing substantially from theproperties of the major portions thereof. If

a such a core is rotated about its axis through a.

single revolution below a suspended astatic magnetic system in which theaxes of the magnets so are generally parallel to the axis of the core,the deflection of the. magnetic system as recorded on a sensitized paperin the type of apparatus herein described will be an irregular lineprobably having more or less sinusoidal form. Suclfa line 35 constitutesa rather uninterpretable record of the 'sum of the various proper es ofthe core.

In accordance with the present invention a. second record is made byturning the core end for v end and rotating it under the magneticsystem, 40 preferably (for simplicity of graphical calcula-. tion) in adirection opposite its former rotation. There is thus obtained anothercurve which, in generahmay have little resemblance to theuon'e firstobtained. From the two curves, however, polarization efiects may bereadily segregated from the effects of anisotropic susceptibility, and

in each of the sub-divisions of these eiijects there may be ratherreadily segregated those portions of the effects which are of interestfrom those which are strictly characteristic of the particu-.

lar core and not of interest. This latter analysis is particularly trueif runs are made on aseries of cores taken close to eachother inthe sameportion of the bore hole; Furthermore, by taking proper precautions inmaking the determinations, other matters of interest are deducible.

The various objects of the invention relating to the preparation ofcores and the making of determinations and details of both methods andapparatus will be apparent from the following description read inconjunction with the accompanying drawings in which:

Figure 1 is a side elevation, partly in section, showing the generallayout of the improved apparatus;

Figure 2 is an end view of the same, also partially in section, to showdetails;

Figure 3 is an enlarged sectional view showing details of the coreraising mechanism;

Figure 4 is a vertical section showing the construction of a micrometerused to accurately locate a core with respect -to the suspended magneticsystem; v I

Figure 5 is a vertical elevation with certain parts in section, showingan improved core holding device;

Figure 6 is an end view of the same;

Figure 'I is a front elevation showing the improved recording camera;

Figure 8 is a side elevation of the same;

Figure 9 is a fragmentaryview, partially in section, showing the drivingmechanism for the core;

Figure 10 is a section of the same on a vertical plane;

Figure 11 is a wiring diagram illustrating the interconnections betweenvarious portions of the apparatus;

Figures 12, 13 and 14 are diagrams showing the types of records obtainedin the apparatus, and their mode of analysis;

Figure 15 isa vertical section illustrating one method of preparingcores for determinations; and

Figure 16 is a diagrammatic illustration of an alternative method ofmaking determinations.

Referring first to Figures 1 to 4, inclusive, the various portions ofthe apparatus are illustrated as supported upon a sturdytable 2 arrangedto prevent vibration to a maximum degree, and preferably carefullyleveled to properly support a magnetic system. This table carries amagnetic shield 4. for example, of steel of considera-ble thickness,provided with a window at its teeth of this rack mesh with a pinion 30adapted lower end of suflicient size to permit entry of a core and itsholder. Fixed in the upper portion of this shield is a magnetometerhousing 6 consisting .of a torsion wire enclosing tube and a lowerdamping housing 8, both formed of nonmagnetic material. Within thishousing there is located a pair of bar magnets l and i2, of equaldimensions and supported upon a suitable mounting carrying a mirror II,the whole structure being supported by a torsion wire of suitable lengthadjustable about its axis by means, generally indicated at I8, of thetype usually provided on sensitive galvanometers. Such suspensions forastatic magnetic systems are well known and need not be furtherdescribed. Windows are provided in the housing and'the shield 4 oppositethe face of the mirror.

Ehrtending downwardly through the table is a tube 20 in which isslidably mounted a tube 22 carrying a core holder and counter-balancedby weights 24 supported by pulleys 26. A rack 28 carried by the tube 22acts as a spline with respect to the bearing portions of the tube 20 toprevent rotation of tube 22 about its axis. The

to be driven by a hand wheel 34 through a shaft 32 arranged to beclamped in fixed position by clamping means 35, actuated by a clampingscrew 38. The parts just described are accurately arranged so as todefinitely align a core carried by the holder with respect to themagnetic system.

The core holder is shown in detail in Figures 5 and 6. The tube 22 atits upper end carries a base plate 40 at one end of which there islocated a standard 42 in which is journalled a sleeve 44 carrying asprocket 46. Over this sprocket is trained a chain 48 which extendsdownwardly through the table and passes about a sprocket 50 arranged tobe driven by a motor 52 through reduction gearing, as hereafterdescribed.

The core holder proper, which is removable from base plate 40, comprisesa base 54 on which are adjustably mounted two standards 56 and 58. Theformer of these has journalled in its upper end a face plate 60 providedwith an axially extending pin 62 adapted to enter a hole formed in oneend of a core C. The second standard 58 is provided with a face plate 64carried by a shaft 66 which is slotted, as indicated-at 48, to receive akey carried by the sleeve 44 with the result that the shaft 55 and theface plate 54 are rotated with the sprocket 46. Due to the key and slotconstruction, the shaft 58 is removable lengthwise from the-sleeve 44.The face plate 64 carries not only a central pin corresponding to thepin 52, but in addition an eccentric driving pin I2 arranged to engagean eccentric hole in the core C and thereby drive the same. In order toclamp the standards 56 and 5 in fixed position they are provided,respectively,

with headed members 14 and 16, arranged to slide in a T-slot l8. Handles80 and 82 are connected to transverse pins having eccentric portionsengageable within openings in the members 14 and I6 so that manipulationthereof will effect clamping and definite location of the standards infixed position. Each of the standards is provided with key members 84engageable within the narrow portion of the T-slot II for accurateguidance. The base 54 is adapted to 'be maintained accuratelyflxedrelative to the base plate by having holes therein arranged toengage pins 85 carried by the stand: ard 42 and by being arranged to beclamped on the base plate by means of a clamping screw 88.

The base 54 is provided with a tubular standard ll having a splitportion at its upper end arranged to be clamped by a collar and clampingscrew arrangement 94 upon an anvil member 98. This anvil member isadjustable to a definite height, preferably that of a horizontal planetangent to the upper side of the core and is arranged when the core islocated adjacent the magnetometer to abut the lower end of a micrometerscrew 98, the longitudinal position of which is determined by therelationship of a head llll with respect to the supporting nut I02. Bythe proper location of the anvil with respect to the core and theadjustment of the micrometer screw, the position of the core withrespect to the magnetic needles is determined to a high degree ofaccuracy.

It is also important that the core should be arranged symmetrically withrespect to the axis of suspension of the magnets. To attain this endtapped holes I04 are located in the base 54 to receive screws holding ablock I06 against the 2,217,788 base 54. Pivotally mounted in the blockI06 is a blade I08 adjustably clamped by a screw H0 and provided with apoint II2 adapted to be located in close proximity with the surface ofIthejcore C. The standards 56 and 5,8 are adjusted with the core betweenthem until a line representing the "center 'of the corelbetween its endfaces is lined holder must be free of all traces .ofmagnetic material.This remark applies not only to the various parts illustrated inFigures. and 6, but the driving chain 48 as well. Freedom from magneticmaterials may be readily determined by a test 'runwith anon-magneticdummy core. If magneti'c'materials are present even inminute quantities noticeable deflections of the magnetometer will beobserved.

The recording camera is generally illustrated at I I4 and in greaterdetail in Figures 7 and 8. It

comprises a light-tight box H6 in which is mounted a drum 8 arranged toreceive a sheet ofphotographic paper which is clamped by a clampingmember extending lengthwise of the drum. The drum is driven throughreduction gearing by means of a synchronous motor I20 .and its shaft isprovided with an insulating disc II1 carrying conductor I2I adapted toengage and thereby connect with each other contact members I23. Theobject of this arrangement will be described hereafter. A knob H9 isconnected to the drum and serves to move it, with the disc I I1,relative toits driving gearing which is provided with a slippingconnection therewith. The knob. H9 is preferably provided with a pointermoving adjacent a fixed scale so that the position of the drum may bereadily determined.

Ilhunination for the magnetometer recording is provided by means of alamp I22 carried within a tube I26 extending transversely across thecamera box I I8 and arranged for angular adjustment by means of a knobI28. Adjacent the central portion of thistube and mounted within thesame is located a reflecting prism I24 arranged to refleet a beam oflight from the lamp to the mirror I4 through an aperture in the box I I6. A lengthwise extending opening I3I is provided in the camera box andis adapted to be covered by a shutter I34, which is normally in positionclosing the box against the entrance of light, and when in suchposition, renders visible a scale carried by it to facilitate adjustmentby observing the position of a spot of light thereon. When a record isbeing made, this shutter is manually raised by manipulation of knob I35,so that the beam may enter the box.

The optical system is of substantially conventionalform. The beam of.light from the prism I24 passes through a lens I30 (Figure l) to themirror I4 by which it is reflected back through the lens I30 and throughthe slot I3I. The lens I30 is a cylindrical lens having its axisvertical light in traversing it twice would be focused to a very thinvertical line at the position of the pa shutterclosedthere will appearon the scale of the shutter a vertical line, and adjustments may be madeusing this spot as aguide to the condition of the instrument. When theshutter is open. a corresponding point .of light is-projected uponthepaper. r

Inasmuch as a single determinationmay take a time of the order ofone-half to two hours, the

apparatus is preferably made as automatic as possible in order to avoidthe necessity for constant attendance Furthermore, adjustments must bepossible and for this reasonthere are provided certain details, asillustrated in Figures 9 and and the wiring diagram of Figure'll.

The apparatus for driving the core through the chain 48, brieflyreferred to heretofore, is illustrated in greater diagrammatic detail inFigures 9 and l0. -The motor 52 drives through reduction gearing,indicated at I40, a shaft I42 carrying worms I46 and I48. These Wormsmesh, respectively, with worm wheels I50 and I52, respectively, securedto shafts I53 .and I55, to which are secured pinions I54an'd I56. A gearI58,

journalled on a pin carried by a' lever I60 is adapted to meshselectively withthe pinions I54 and I56 when the lever I60 is swung intoalternative positions about a boss -I62 carried by a portion of theframe which mounts these elements, and at the lower end of the tube 22.The adjustment of the lever and its alternative positions is effected bymeans of a link I64 joining it toa manually operable knob I66 which maybe held in its adjusted position by a clamping screw I68. The knob I66is operatively connected to the actuating lever of a switch I10 which isarranged to be closed when the lever I60 is in one position and openedwhen the lever I60is in its other position.

The gear I58 meshes with a gear I12 which is keyed to a shaft I14mounted-in the boss I62 and held against axial movement with respectthereto. I14 to freely turn thereon, and about it is trained Thesprocket 50 is journalled on the shaft the chain 48 which is held tautby an adjustable I14. When the cam I84 is in the position shown inFigure 10, the spring is relieved of compres- 'sion and the sprocket 50may turn freelv about the shaft I14 so that the position of the core maybe adjusted independently of the driving gearing. On the other hand. ifthe cam lever I84 is moved outwardly, the spring I80 is compressed,clamping the sprocket wheel 50 between the gear I12 and the disc I18 andthus causing it to be driven by the gear.

The disc I18 carries a bridging conductor arrangement I86 adapted toconnect contacts I88, thereby forming a switch. This arrangement issimilar to that heretofore described and comprising the elements I2I andI23.

Referring now to the wiring diagram of Figure 11, various elementsheretofore mentioned wiIl be recognized therein. Power for the entiresystem is derived from an alternating current line I90. In view of thefact that both'the core driving motor 52 and the camera driving motorI20 are synchronous motors driven from this same line, it is obviousthat the rotation of the core and camera drum will accuratelycorrespond; Howcarefully prepared, for example, by having its ever, thecore and the camera drum are not driven at the same rotary rate. Whenthe core makes a complete revolution the camera drum turns through only350 degrees. In such fashion, a record corresponding to a completerotation of the core is confined to a clear portion of the photographicpaper on the camera drum, 10 being allowed for the overlapping andclamping of the paper thereon. Desirably, the scale heretofore referredto in connection with the knob H9 is graduated in terms of corepositions rather than drum positions. In other words, 350 is graduatedto correspond to 360' of the core rotation.

The contact members I86 and I2I of the discs I18 and II I, respectively,are also arranged to correspond with each other. The former, which maybe designated the magnetometer limiting switch'is so related to thecontacts I88, which are conventionalized in Figure 11, as to short thesecontacts between 359 and 1 of a core revolution. The zero position of acore should correspond to a mid position of this shorting contact. Thecamera limiting switch, on the other hand, is so arranged that theconductor I22 shorts the contacts I 23 between 355 and 5 of the cameradrum rotation.

Th electrical relationships of the various parts will be generally clearfrom the wiring diagram of Figure 11 without detailed description. Adouble pole double throw switch I94 is so arranged that the motor 52 maybe driven for adjustment and testing purposes independently of the motorI20 or simultaneously therewith, while both are under control of therelay contact I96, arranged to be opened through energization of therelay 0011 I98. When opening of the motor circuits takes place due toenergization of the coil I98,

a contact is made to energize a warning bell 2I2,

Mounted on the shaft I 53 there is a toothed" cam member 202, adapted tocontrol a quickmake and break switch 204. The arrangement is such thatduring rotation of the cam member 202 contact. is made for short periodsand broken for still shorter periods so as to produce a dotted record onthe photographic paper. The switch I10 referred to heretofore andillustrateddn Figure 9 is arranged'to short the contacts 204 during aforward run, so that the record made during a forward run will be acontinuous, unbroken line, while during a reverse run, a dotted linewill be produced.

Additionally, on the wiring diagram there will be noted a protectiveresistance 206 and a switch 208 serving to energize the lamps I 22 andI31 independently of the rest of the apparatus.

In the use of the apparatus, the core is first cylindrical face turneddown and its ends ground at right angles to its axis with due precautionto avoid the inclusion in the core of any magnetic materials such asiron chippings or the like. The core thus prepared is mounted in theholder, illustrated in Figures 5 and 6, and centered in predeterminedposition by means of the member I08. There is also marked on the core azero indication from which angular reference about the axis may be made.

An alternative mode of preparation of the core for mounting in theapparatus is illustrated in Figure'15. It sometimes happens that coresas obtained from a core barrel are broken and may have rather irregularsurfaces, breaks and hollows occurring along or adjacent to the lines ofseparation of the various strata. The cores in such cases may be ratherfragile and even though major breaks are mended by the use of amagnetically neutral adhesive, such as casein glue, there may be dangerof breakage if the core is subjected to turning and boring preparatoryto mounting.

Additionally, there may be some question of demagnetization ormagnetization in a strong electric field such as that of the earth ifthe core is subjected to much shock during its preparation. The turningaccomplished by a grinding wheel may possibly affect its magneticproperties, and the same is true of the provision of holes at the endsfor mounting purposes.

These various difficulties may be avoided by ensand blast, in view ofthe extremely small mass' of the particles of sand, does not appreciablyvibrate the core to such extent as to affect its magnetic properties.Following such sand blast, the core is set upon end upon three adjustingscrews threaded into a baseboard. By the adjustment of these screws theaxis of the core may be brought to accurate perpendicularity withrespect to the base, whereupon it is surrounded concentrically by aninternally smooth cylindrical mold and surrounded by plaster of Paris,which is permitted to set. The mold may then be removed and theadjusting screws threaded out of the plaster of Paris with the resultthat there remains a smooth cylindrical surface concentric with the axisof the core. The plaster of Paris ends may then be bored to receive themounting and driving pins. Figure 15 illustrates a core 250 which isshown as involving various surface defects. This is surrounded by thecase 252 of plaster of Paris, which is bored at 254, 256 and 258 toreceive the mounting and driving pins. The screws on which the core wasoriginally supported will leave holes, as indicated at 260, but

these are of no consequence. Paris is so soft that the mounting anddriving holes may be formed therein without any substantial vibration ofthe core.

When the core and its holder are located on the member 40 with the shaft66 splined to the sprocket 46, the core may be located in predeterminedrelationship with the magnetic system, the lamp I22 turned on and thecore rotated by hand manipulation of the chain 48 to determine whetherthe position is such that the beam of light will remain on the scale I34during the complete revolution and also that the beam is properlycentered. Centering may be effected throughthe manipulation of theadjustment I8 for the magnet suspension, while if greater or lesssensitivity is desired the support may be lowered, the micrometer resetand the core again brought into the position determined by the newsetting of the micrometer. In general, it is desirable that The plasterof the throw of the beamof light on the scale should be the maximumconsistent with maintaining it within the scale limits.

Such adjustments having beeneflected, and photographic paper located onthe drum* II8, a

. zero line is traced by hand rotation of the-camcore and the-locationof the contacts I86 and I88, 15

as shown in Figure 9; The gear I58 is meshed with the gear I54 toproducea forward rotation of the core with the result that theswit'ch I10 isclosed to short circuitthe dotting switch 204. The room containing theapparatus may then be darkened and the shutter I34, raised to expose thepaper through the slot I3I.

With the switch I94 in its lower position, the switch 200 is closed,initiating the operation of the apparatus. At the time of thisinitiation of the operation, it .will be noted that the contacts of boththe magnetometer and camera limit switch will be closed. The contacts ofthe camera limit switch IIl short circuit the relay coil I98 so that thelatter will not attract its armature I96, and the switch 200 will,therefore, initiate rotation of both motors 42 and I20 and will alsoenergize the transformer I92, the switch 288 being open at this time.The resistance 206 prevents a short circuit of the line. Switch I23opens its circuit before switch I88 opens its circuit so that theoperation is not stopped.

As the core rotates, the magnet system will be deflected causing a spotof light to move across the sensitized paper on the camera drum and thustrace a record.- At the same time, the lamp I31 produces a mark servingto indicate the right side of the photographic record. The core ispreferably very slowly driven in order that the magnets may follow itand in order that temporary jarring of the beam of light due to causesother than the magnetic conditions of the core will fail to recordbecause the exposures corresponding to them will be very short. Sincethe dotting switch is shorted a solid line record will be made. 1

When the core has rotated 359 the contact I85 will bridge the contactsI88. At the same time,however, the contact I 2I will not have bridgedthe contacts I23 because the camera will have rotated only about 349.Accordingly, the relay I98 is energized, opening the motor and lampcircuits and at the same time energizing the warning bell 2I2. Theoperator will then close the shutter I34, thus ending the record of theforward run.

The core is then removed from its support, turned end for end andreplaced in the same position relative to the magnets as before, thisposition being determined accurately by the micrometer. The gear I58 isthen meshed with the pinion I56 and the core and camera drum reset intheir zero positions as before. Simultaneously with the adjustment ofthe gear I58, the switch IIIl is opened. The shutter I34 may now beraised and the switch 200 closed to provide a reversed rotation of thereversed core. The record the record produced during the forward run.Automatic stopping takes place as before.

After development of the. paper on the drum IIB, the curves thereon maybe interpreted to secure the desired information relative to themagneticcharacteristicsof the core. Figures 12, I i 13 and 14 indicate the typesof records which may be obtained and theirinterpretation, though it 1will be understood that individual coreswill show peculiar results' inthe curves made therefrom which may have special significance.

Consider first the record illustrated in Figure 12, made on a sheet 2I4.As illustrated, this record would be of the type obtained from a core Ishowing polarization only and in which the polarization was fairlyuniform. The record made during the forward-run is indicated at 2I6 andthat during the reverse run at 2I8. The line'228 is the line tracedbythe lam' I31 during both runs. y I

With a core of the type just mentioned the two curves will besubstantially symmetrically located about the mean axis. Theoretically,if uniform polarization existed a'smooth sinusoidal curve would resultfrom both runs and the two would be identical in shape but locatedopponature, exhibiting a definite. axis throughout the core, the curveto be expected on a record such as that of Figure 13 would be a smoothsinusoidal curve consisting of two cycles on the length of the record.Furthermore, the records formed during the forward and reverse rotationswould coincide. Actually, due to local irregularities, non-coincidentrecords, as indicated at 222 and 224, will be produced, while,furthermore, the

curve will not exhibit sinusoidal symmetry about its axis due to lack ofsymmetry of its anisotropic susceptibility about any axis.

The two records so far discussed are rather more theoretical than.actual. Actually, both polarization and susceptibility are most likelyto be present. To exhibit the type of record obtained in such a case,and in order to make it comparable with the others, there is illustratedin Figure 14 the type of record which would result if a single core hadthe polarization which would give rise to Figure 12 if it existed alone,and the anisotropic susceptibility which would give rise to Figure 13 ifthat existed alone. It will be noted that in the case of Figure 14,

the forward and reverse curves 221 and 228 bear no recognizablerelationship to each other. However, these two curves taken together maybe interpreted to give separate information relative to polarization andanisotropic susceptibility. Consider, for example, the spacing of thecurves transverse to their axis at any particular point, as, forexample, at the point indicated in Figure 14 where this spacing is 2a.One-half of this spacing, namely, a, is the corresponding deviation fromthe axis due to polarization. On the other hand, the quantity b,representing the deviation from the axis due to anisotropicsusceptibility may be readily determined by noting the deviation fromthe axis of the center point of the line indicated at 2a in Figure 14..The figures will make clear how the two results superimpose to producethe record of Figure 14, and how that record may be analyzed to give thedeviations due to the two causes. By plotting from Figure 14 the curvessuch as those in Figures 12 and 13, which are deducible from Figure 14,there may be obtained the still further information which may be derivedfrom the irregularities and lack of symmetry of these curves. Forexample, a small inclusion of a particle of magnetic material may, ifthe material is polarized, exhibit itself by a sharp deviation fromsmoothness of either one or both of the derived curves.

It will be noted that the careful marking of the core to indicate itszero position will enable the record to be correlated with the core insuch fashion that there may be marked on the core or tabulated for itthe various magnetic and susceptibility axes and the like which may beof interest for the purpose of interpreting the conditions of thesub-surface where the core was taken. Desirably, to determine conditionsin any local region, a number of cores from that region should beexamined so that in the interpretation only the factors common to thatregion may be given weight and proper disregard taken of the propertieswhich are solely characteristic of the individual cores. As indicatedabove, the principal matter of interest is to determine the polarizationaxis or the axis of maximum susceptibility which may be deduced to liein the general direction of the magnetic field of the earth Theorientation of strata shown in the cores may be deduced therefrom.

In Figure 16 there is illustrated an alternative arrangement forsecuring the type of information indicated above. In this case, theastatic magnetic system supported by a suspension wire 250 comprisesmagnets 252 and 254. A core 256, located as illustrated, with its axissubstantially parallel to the axis of the suspension, may be rotated toproduce a first trace on the record sheet. The core is then moved to theposition indicated at 256' so that its axis is located at a distancefrom the axis of suspension the same as before with the core at the samevertical height withrespect to themagnetic system and at the samedistance as before from the lower magnet and similarly spaced from theopposite end of the magnet. If the core in the position 256' is on thesame side of the magnet 254 as in the position 256, its rotation shouldbe in the opposite direction to secure records of the types indicated inFigures 12 to 14. On the other hand, if it ison' the opposite side ofthe magnet, its direction of rotation shouldbe the same in both cases.Under these circumstances, the results will be of the same'general typeas those described heretofore, and a similar analysis may be made. I

What I claim and desire to protect by Letters Patent is:

1. In combination, a suspended-magnetic system, means for mounting acore from a bore hole for rotation about an axis perpendicular to theaxis of suspension of said system, means for providing a photographicrecord of deflections of said system, means for rotating in bothdirections a core so mounted, and means for distinguishing records ofdeflections produced during rotation of a core in one direction fromthose produced during rotation of the core in the opposite direction.

2. In combination, a suspended magnetic system, means for mounting acore from a bore hole for rotation about its axis adjacent to saidsystem, means for providing a photographic record of deflections of saidsystem, means for rotating in both directions .a core so mounted, andmeans for distinguishing records of deflections produced during rotationof a core in one direction from those produced during rotation of thecore in the opposite direction.

3. In combination, a suspendedmagnetic system, means for mounting a corefrom a bore hole for rotation about an axis perpendicular to the axis ofsuspension of said system, means for providing a photographic record ofdeflections of said system, means for rotating in both directions a coreso mounted, and means for distinguishing records of deflections producedduring rotation of a core in one direction from those produced duringrotation of the core in the opposite direction, the last named meansbeing automatically controlled by reversal of the direction of rotationof the core.

4. In combination, a suspended magnetic system, means for mounting acore from a bore hole for rotation about its axis adjacent to saidsystem, means for providing a photographic record of deflections of saidsystem, means for rotating in both directions a core so mounted, andmeans for distinguishing records of deflections produced during rotationof a core in one direction from those produced during rotation of the-core in the opposite direction, the last named means beingautomatically controlled by reversal of the direction of rotation of thecore.

5. In combination, a suspended magnetic system, means for mounting acore from a bore hole, for rotation about an axis perpendicular to theaxis of suspension of said system, means for providing a photographicrecord of deflections of said system, means for rotating in bothdirections a core so mounted, and means for distinguishing records ofdeflections produced during rotation of a core in one direction fromthose produced during rotation of the core in the opposite direction,the last named means acting by periodically interrupting a recordingbeam of light during rotation of the core in one direction.

6. In combination, a suspended magnetic system, means for mounting acore from a bore hole for rotation about its axis adjacent to saidsystem, means for producing a photographic record of deflections of saidsystem, means for rotating in both directions a core so mounted, andmeans for distinguishing records of the deflections produced duringrotation of a core in one direction from those produced during rotationof the core in the opposite direction, the last named means acting byperiodically interrupting a recording beam of light during rotation ofthe core in one direction.

7. In combination, a suspended magnetic system, means for mounting acore from a bore hole for rotation about an axis perpendicular to theaxis of suspension of said system, and means carrying said mountingmeans for movement towards or from said system, the mounting means beingremovably slidably mounted with respect to said carrying means at rightangles to the direction of said movement towards or from said system.

JOHN M. PEARSON.

